Linux kernel mirror (for testing)
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linux
1// SPDX-License-Identifier: GPL-2.0
2
3//! Extensions to the [`alloc`] crate.
4
5#[cfg(not(test))]
6#[cfg(not(testlib))]
7mod allocator;
8pub mod box_ext;
9pub mod vec_ext;
10
11/// Indicates an allocation error.
12#[derive(Copy, Clone, PartialEq, Eq, Debug)]
13pub struct AllocError;
14
15/// Flags to be used when allocating memory.
16///
17/// They can be combined with the operators `|`, `&`, and `!`.
18///
19/// Values can be used from the [`flags`] module.
20#[derive(Clone, Copy)]
21pub struct Flags(u32);
22
23impl Flags {
24 /// Get the raw representation of this flag.
25 pub(crate) fn as_raw(self) -> u32 {
26 self.0
27 }
28}
29
30impl core::ops::BitOr for Flags {
31 type Output = Self;
32 fn bitor(self, rhs: Self) -> Self::Output {
33 Self(self.0 | rhs.0)
34 }
35}
36
37impl core::ops::BitAnd for Flags {
38 type Output = Self;
39 fn bitand(self, rhs: Self) -> Self::Output {
40 Self(self.0 & rhs.0)
41 }
42}
43
44impl core::ops::Not for Flags {
45 type Output = Self;
46 fn not(self) -> Self::Output {
47 Self(!self.0)
48 }
49}
50
51/// Allocation flags.
52///
53/// These are meant to be used in functions that can allocate memory.
54pub mod flags {
55 use super::Flags;
56
57 /// Zeroes out the allocated memory.
58 ///
59 /// This is normally or'd with other flags.
60 pub const __GFP_ZERO: Flags = Flags(bindings::__GFP_ZERO);
61
62 /// Allow the allocation to be in high memory.
63 ///
64 /// Allocations in high memory may not be mapped into the kernel's address space, so this can't
65 /// be used with `kmalloc` and other similar methods.
66 ///
67 /// This is normally or'd with other flags.
68 pub const __GFP_HIGHMEM: Flags = Flags(bindings::__GFP_HIGHMEM);
69
70 /// Users can not sleep and need the allocation to succeed.
71 ///
72 /// A lower watermark is applied to allow access to "atomic reserves". The current
73 /// implementation doesn't support NMI and few other strict non-preemptive contexts (e.g.
74 /// raw_spin_lock). The same applies to [`GFP_NOWAIT`].
75 pub const GFP_ATOMIC: Flags = Flags(bindings::GFP_ATOMIC);
76
77 /// Typical for kernel-internal allocations. The caller requires ZONE_NORMAL or a lower zone
78 /// for direct access but can direct reclaim.
79 pub const GFP_KERNEL: Flags = Flags(bindings::GFP_KERNEL);
80
81 /// The same as [`GFP_KERNEL`], except the allocation is accounted to kmemcg.
82 pub const GFP_KERNEL_ACCOUNT: Flags = Flags(bindings::GFP_KERNEL_ACCOUNT);
83
84 /// For kernel allocations that should not stall for direct reclaim, start physical IO or
85 /// use any filesystem callback. It is very likely to fail to allocate memory, even for very
86 /// small allocations.
87 pub const GFP_NOWAIT: Flags = Flags(bindings::GFP_NOWAIT);
88}